ES2796249T3 - Cellulosic barrier composition comprising anionic polymer - Google Patents

Abstract

A composition comprising a) cellulose fibers, having a number average length of 0.001 to 0.2 mm and a specific surface area of 1 to 100 m2 / g and comprising microfibrillar cellulose fibers; b) an at least partially hydrolyzed vinyl acetate polymer; and c) at least one anionic polymer wherein the composition comprises 55 to 65% by weight of a) and 35 to 45% by weight of b) based on the dry weight of a) and b) in the composition; as well as 0.1 to 3% by weight of c), based on the dry weight of a), b) and c) in the composition.

Description

DESCRIPTION

Cellulosic barrier composition comprising anionic polymer

Technical field of the invention

The present invention relates to a composition comprising cellulosic fibers, to an at least partially hydrolyzed vinyl acetate polymer and an anionic polymer, a self-supporting film formed from such a composition, to a method for producing such a self-supporting film, to a multilayer article comprising such a composition or such a self-supporting film disposed on a substrate, to a method for the production of such a multilayer article and to the use of said composition or such a self-supporting film to provide a barrier to a permeable substrate.

Technical background of the invention

Barriers find their use in many applications. For example, in many food packaging applications, there is a need to protect food from oxygen to prevent oxidation of food components, which could reduce the quality and / or flavor of the food. This can be done by using a material that has low oxygen permeability, conventionally called an oxygen barrier.

Other barrier properties that may find use in the packaging of food and other items are obvious to the person skilled in the art and include barriers to liquids, vapors, aromas, fats, microorganisms, etc.

While there is a need for barriers, there is also a desire to provide such barriers that are largely based on material from renewable sources.

Cellulosic fibers, such as microfibrillar and / or highly refined cellulose fibers, have previously been investigated, eg, for use in barriers.

WO00 / 05310 relates to processes and materials in which highly refined cellulose fibers are broken down into microfibers and other processes into compositions, films, coatings and solid materials that are biodegradable and even edible.

WO2009 / 123560 relates to compositions comprising microfibrillated cellulose and one or more polysaccharide hydrocolloids, and the use of such compositions, among others, to provide a barrier on a sheet of paper.

Document WO2006 / 056737 refers to bio-composite materials comprising cellulose fragments, 5 to 55% by weight of hydrophilic binders and 5 to 65% by weight of hydrophobic binders, and the use of such materials as a high strength material which is impermeable to water.

US 6183596 relates to a paper coated with a microfibrillated cellulose-containing coating material, and describes surface size coating materials comprising 0.1-10% by weight of super microfibrillated cellulose which is added to conventionally known coating materials. .

US 2001/004869 describes compositions comprising essentially amorphous cellulose nanofibrils, at least one additive chosen from carboxycellulose with a degree of substitution of more than 0.95, a natural polysaccharide, a polyol and an optional co-additive, the content of the additive being y the optional co-additive less than or equal to 30% by weight, relative to the weight of nanofibrils, additive and optional co-additive.

However, there is still a need to provide barrier materials with improved performance in terms of physical and mechanical properties, e.g. eg, permeability, tensile strength, stiffness, and pliability.

Summary of the invention

An object of the present invention is to at least partially meet the needs in the art and to provide a barrier based on a significant amount of material from renewable sources that have good barrier properties.

Another object of the present invention is to provide a barrier based on a large amount of material from renewable sources and which has good physical properties, especially mechanical resistance.

The present inventors have surprisingly found that these and other objectives can be achieved by forming layers, such as self-supporting films and cover layers, from certain compositions comprising cellulose fibers, an at least partially hydrolyzed vinyl acetate polymer and at least one anionic polymer, as defined in claims 1.8, 10, 13, 15 and 19.

Although it is largely based on material from renewable sources, a self-supporting film or coating layer formed from such compositions has been shown to exhibit excellent properties. mechanical and barrier properties.

Therefore, in a first aspect, the present invention relates to a composition as defined in claim 1. The composition comprises a) cellulose fibers having a number average length of 0.001 to 0.2 mm and a specific surface area from 1 to 100 m2 / g; b) an at least partially hydrolyzed vinyl acetate polymer; and c) at least one anionic polymer, wherein the composition comprises 55 to 65% by weight of a) and 35 to 45% by weight of b) based on the dry weight of a) and b) in the composition; as well as 0.1 to 3% by weight of c), based on the dry weight of a), b) and c) in the composition.

In a second aspect, the present invention relates to a method for the manufacture of a self-supporting film as defined in claim 8 and comprising the steps of forming a film from a composition according to a support surface, removing at least part of the water in said composition and remove the self-supporting film thus formed from said support surface.

In a third aspect, the present invention relates to a self-supporting film as defined in claim 10 and formed from a composition as defined above.

In a fourth aspect, the present invention relates to a multilayer article as defined in claim 13 and comprising a substrate and a layer of a composition or a self-supporting film as defined above arranged on at least one side of said substrate .

In a fifth aspect, the present invention relates to the use as defined in claim 19 of a self-supporting composition or film as defined above to provide a barrier to a permeable substrate. These and other aspects of the invention will now be described in more detail.

Detailed description of the invention

A composition of the present invention comprises at least the following components in addition to water: a) cellulose fibers having a number average length of 0.001 to 0.2 mm and a specific surface area of 1 to 100 m2 / g;

b) an at least partially hydrolyzed vinyl acetate polymer; and

c) at least one anionic polymer.

The amount of cellulose fibers a) in a composition of the present invention is 55 to 65% by weight based on the dry weight of a) and b) in the composition.

The amount of the at least partially hydrolyzed vinyl acetate polymer b) in a composition of the present invention is 35 to 45% by weight based on the dry weight of a) and b) in the composition.

The amount of the at least one anionic polymer c) in a composition of the present invention is 0.1, even more preferably 0.3, most preferably 0.5 to 3, and most preferably 2% by weight of the dry weight of a), b) and c) in the composition.

The composition of the present invention comprises 55 to 65% by weight of a) cellulose fibers having a number average length of 0.001 to 0.2 mm and 35 to 45% by weight of b) a vinyl acetate polymer to less partially hydrolyzed, based on the dry weight of a) and b) in the composition, and 0.1 to 3% by weight of c) at least one anionic polymer, based on the dry weight of a), b) and c) in the composition.

Preferably a), b) and c) together constitute at least 90, most preferably at least 95 and in some cases even 100% by weight of the dry weight of a formulation of the present invention.

The composition of the present invention is preferably free of or comprises less than 5% by weight, based on the dry weight of the composition, of hydrophobic binders. Examples of such hydrophobic binders include hydrophobic polymers comprising epoxies (such as bisphenol-A or modified bisphenol-A epoxies), polyurethanes, phenolic resins, hydrophobic acrylics, and siloxanes.

The cellulose fibers contemplated for use as component a) in the present invention have a number average length of 0.005, preferably 0.01, more preferably 0.02 to 0.2, more preferably 0.1 mm and a specific surface area of 1, preferably 1.5, more preferably 3 to 100, preferably 15, most preferably 10 m2 / g (as determined by adsorption of N ² at 177 K according to the BET method using a Micromeritics ASAP 2010 instrument).

The number average width of the cellulose fibers is preferably 5, more preferably 10, most preferably 20 to 100, more preferably 60, most preferably 40 pm (measured with an L&W fiber tester) .

As used herein, the term "number average" as used in number average length and number average width refers, for example, in the context of fiber length, to the arithmetic mean or Average length of individual fibers, as determined by measuring the length of n fibers, adding the lengths, and dividing by n.

Sources of cellulose for use in this invention include, but are not limited to, the following: wood fibers, for example, hardwood or softwood derivatives, such as chemical pulps, mechanical pulps, thermomechanical pulps, mechanical pulps treated with chemicals, recycled fibers or newsprint; seed fibers, such as cotton; whole seed fiber, such as soy hulls, pea hulls, corn hulls; bast fibers, such as flax, hemp, jute, ramie, kenaf; leaf fibers, such as manila hemp, sisal hemp; stalk or straw fibers, such as bagasse, corn, wheat; grass fibers, such as bamboo; cellulose fibers from algae, such as velonia; bacteria or fungi; and parenchymal cells, such as those of vegetables and fruits. The source of the cellulose is not limiting, and any source can be used, including synthetic cellulose or cellulose analogs.

In embodiments of the present invention, the cellulose fibers comprise microfibrillar cellulose fibers.

For the purposes of the present invention, microfibrillar cellulose refers to small diameter, high length-to-diameter ratio substructures that are comparable in dimensions to those of cellulose microfibrils that occur in nature.

According to one embodiment, the microfibrillar cellulose is modified eg by grafting, crosslinking, chemical oxidation, eg by use of hydrogen peroxide, Fenton reaction and / or TEMPO; physical modification such as adsorption, for example chemical adsorption; and enzymatic modification. Combined technologies can also be used to modify microfibrillar cellulose.

Cellulose can be found in nature at various hierarchical levels of organization and orientation. Cellulose fibers comprise a layered secondary wall structure within which macrofibrils are arranged.

Macrofibrils comprise multiple microfibrils that further comprise cellulose molecules arranged in crystalline and amorphous regions. Cellulose microfibrils range in diameter from 5 to 100 nanometers for different plant species, and are most typically in the range of 25 to 35 nanometers in diameter. Microfibrils are present in clusters that are arranged in parallel within a matrix of amorphous hemicelluloses (specifically xyloglycans), pectin polysaccharides, lignins, and hydroxyproline-rich glycoproteins (includes extensin). The microfibrils are approximately 3-4 nm apart with the space occupied by the matrix compounds listed above. The specific arrangement and location of matrix materials and how they interact with cellulose microfibrils is not yet fully understood.

Microfibrillar cellulose is typically prepared from native cellulose fibers that have been delaminated into small pieces with a large proportion of the microfibrils from the fiber walls uncovered.

Delamination can be carried out in various devices suitable for delaminating cellulose fibers. The prerequisite for the processing of the fibers is that the device is capable or controlled in such a way that the fibrils are released from the fiber walls. This can be achieved by rubbing the fibers against each other, the walls, or other parts of the device in which delamination takes place. According to one embodiment, delamination is carried out by pumping, mixing, heat, steam explosion, pressurization-depressurization cycle, impact milling, ultrasound, microwave explosion, grinding, and combinations thereof. In any of the mechanical operations described herein, it is important that sufficient energy is applied to provide microfibrillar cellulose fibers. In one embodiment, microfibrillar cellulose fibers are prepared by treating a native cellulose in an aqueous suspension comprising an oxidant and at least one transition metal, and mechanically delaminating the native cellulose fibers into microfibrillar cellulose fibers.

Methods for the preparation of microfibrillar cellulose fibers suitable for use in the present invention include, but are not limited to, those described in WO 2004/055268, WO 2007/001229 and WO 2008/076056

Non-delaminated cellulose fibers are different from microfibrillary fibers in that the fiber length of non-delaminated cellulose fibers generally ranges from 0.7 to 2 mm, and their specific surface area is generally 0.5 to 1.5 m2 / g.

As used herein, the term "at least partially hydrolyzed vinyl acetate polymer" refers to any vinyl acetate polymer, including vinyl acetate homopolymers and copolymers formed from vinyl acetate and al minus one other monomer, where at least a part of the acetate groups are hydrolyzed into hydroxyl groups. Homopolymers are preferred. In the at least partially hydrolyzed vinyl acetate polymer, preferably at least 50%, more preferably at least 90%, most preferably at least 98% of the acetate groups are hydrolyzed to the hydroxyl group.

Polyvinyl alcohol with a degree of hydrolyzation of preferably at least 90, more preferably at least 98% is an example of an at least partially hydrolyzed vinyl acetate polymer especially contemplated for use in the present invention.

The at least partially hydrolyzed vinyl acetate polymer preferably has a weight average molecular weight of 5000, more preferably 25,000, most preferably 75,000 to 500,000, more preferably 250,000, and most preferably 150,000 Da.

The anionic polymers contemplated for use in the present invention can be of synthetic or natural origin, and if they are of natural origin, they can be chemically modified. It should be understood that, for the purpose of the present invention, the anionic polymer c) is different from the b) at least partially hydrolyzed polyvinyl acetate polymer, and from a) cellulose fibers having a number average length of 0.001 to 0.2 mm and a specific surface area of 1 to 100 m2 / g.

Preferably, the charge density of the anionic polymer is 0.1, more preferably 0.2, most preferably 1 to 10, more preferably 8, most preferably 5 meq / g (measured in an aqueous polymer solution at pH 7 using a particle charge detector, Mütek PCD03).

Preferably, the weight average molecular weight of the anionic polymer is 104, more preferably 105, to 108, more preferably 107 Da.

Examples of anionic polymers contemplated for use in the present invention include anionic polysaccharides which can be natural or modified, such as starch, anionic cellulose derivatives, anionic cellulose nanofibers, and anionic polysaccharide gums; and synthetic polymers based on acrylic acid, such as polyacrylic acid. In preferred embodiments of the present invention, the anionic polymer comprises an anionic polysaccharide. More preferably, the anionic polysaccharide constitutes at least 50, such as at least 75, for example at least 95% by weight, or even 100% by weight of the anionic polymer c) in the composition of the invention.

As used herein, cellulose nanofibers refer to cellulose fibrils having a number average length of 100 to 500 nm, and typically a width of 1 to 20 nm, such as 2-10 nm. Methods for the preparation of cellulose nanofibers include, but are not limited to, those described in WO2009 / 069641.

Examples of anionic starches include, but are not limited to, starch oxidized with NaClO and catalytic amounts of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl).

Examples of anionic cellulose derivatives include carboxyalkyl celluloses, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, sulfoethylcarboxymethyl cellulose, carboxymethylhydroxyethyl cellulose, etc., wherein the cellulose is substituted with one or more nonionic substituents, preferably carboxymethyl cellulose.

Examples of anionic polysaccharide gums include natively anionic polysaccharide gums and cationic or non-native polysaccharide gums that are chemically modified to have an anionic net charge.

Polysaccharide gums contemplated for use in the present invention include, but are not limited to, agar, alginic acid, beta-glucan, carrageenan, chewing gum, Dammar gum, gellan gum, glucomannan, guar gum, gum arabic, gum ghatti, gum tragacanth, karaya gum, locust bean gum, mastic gum, psyllium seed husks, sodium alginate, fir gum, tara gum, and xanthan gum, polysaccharide gums are chemically modified, if necessary , to have a net anion charge.

Xanthan gum is a currently preferred native anionic polysaccharide gum for use in the present invention.

In addition to the components a), b) and c) mentioned above, a composition of the present invention may comprise one or more additional components, such as, but not limited to, d) micro or nanoparticles, preferably inorganic micro or nanoparticles.

As used herein, a "microparticle" refers to a solid or amorphous particle that in at least one dimension is less than 100 gm in size, and that in no dimension is greater than 1 mm in size.

As used herein, a "nanoparticle" refers to a solid or amorphous particle that in at least one dimension is less than 100 nm in size and that in no dimension is greater than 1 gm in size. It should be noted that, in the context of the present invention, nanoparticles form a subset of microparticles.

Examples of inorganic micro or nanoparticles contemplated for use in the present invention include silica or silicate-based particles, including colloidal silica particles or silicate particles or aggregates thereof, clays, and metal carbonate particles.

Smectite clays that can be used in the present invention include, for example, montmorillonite / bentonite, hectorite, beidelite, nontronite, saponite and their mixtures. According to one embodiment, the smectite clay is laponite and / or bentonite.

According to one embodiment, the smectite clay can be modified, for example, by introducing a cation or a cationic group, such as a quaternary ammonium group or an alkali metal, for example, lithium.

According to one embodiment, the smectite clay is a lithium-modified synthetic hectorite clay. This clay is for example sold under the name Laponite® from Rockwood or Eka Soft F40 from Eka Chemicals AB. Examples of such clays and the manufacture of such clays include those described in WO 2004/000729. The smectite clay used according to the present invention may have a specific surface area of 50 to 1500, for example 200 to 1200, or 300 to 1000 m2 / g.

Suitable products can be, for example, Bentonite from Süd-Chemie, BASF and Clayton; Bentolite (Bentonite) from Southern Clay Products; and Akzo Nobel hydrotalcite.

If present, the concentration of inorganic microparticles or nanoparticles preferably in a composition of the invention is preferably less than 5% by weight, such as 0.1, preferably 0.3 to 5, preferably 2% by weight based on the dry weight of the total composition.

A composition of the present invention may comprise additional components in addition to those mentioned above.

In one embodiment, the composition of the present invention is a flowable composition, preferably a suspension. A flowable composition of the present invention typically comprises 50, preferably 60, most preferably 70, to 99.9, preferably 95% by weight of water, based on the total weight of the composition. A flowable composition of the invention can be used, for example, to form a coating on a substrate, or to be processed into a self-supporting film, as will be described below.

In another embodiment, the composition of the present invention is a solid, or non-fluid composition, and typically comprises at most 50, preferably at most 20% by weight of water, based on the total weight of the composition.

As shown in the experimental section below, a layer, preferably an essentially coherent layer, such as a self-supporting film, or a coating layer on a substrate, formed from a composition of the present invention, exhibits good barrier properties. and mechanical resistance.

A self-supporting film of the present invention is typically produced by layering a flowable composition of the present invention on a supporting surface, removing at least some of the water from the composition, and removing the self-supporting film thus formed from the supporting surface. Water can be removed from the composition to form a self-supporting film by any conventional means, such as the application of heat, reducing the pressure of the surrounding atmosphere, or by pressure.

The supporting surface can be any surface on which it is possible to layer and remove at least some of the water to form a self-supporting film, such as a flat surface, a drum, an endless belt, a wire cloth, etc.

Therefore, a self-supporting film of the present invention comprises a) cellulose fibers having a number average length of 0.001 to 0.2 mm and a specific surface area of 1 to 100 m2 / g; b) an at least partially hydrolyzed vinyl acetate polymer; c) at least one anionic polymer; and optionally other components.

The details and concentrations of the components in the self-supporting film are those previously described in connection with the composition of the present invention.

As used herein, a "self-supporting film" refers to a film-like article, preferably of a solid material, that does not require support to maintain its structural integrity.

Therefore, a self-supporting film of the present invention typically has the same constituents as the composition from which it is formed. However, in a self-supporting film of the present invention, the water content is significantly reduced compared to a flowable composition of the invention. The water content is removed at least to the extent that a self-supporting film is formed. Water can be essentially removed from the self-supporting film, whereby the amount of water present in the film corresponds to the amount in equilibrium with the surrounding atmosphere.

The thickness of a self-supporting film of the present invention is limited, on the one hand, by the minimum thickness required to produce a self-supporting film and / or the minimum thickness required to obtain the desired barrier properties, and on the other hand by the maximum thickness to which the film can be easily manipulated and produced. Preferably, the thickness of the self-supporting film is in the range of 1, more preferably 5, most preferably 10 to 1000, more preferably 200, most preferably 100 gm. Thicknesses are contemplated of film from 20 to 50 pm.

The self-supporting film can be used alone as such or it can be used as a separate layer in a multi-layer structure.

A multilayer structure of the invention comprises a substrate and a layer, preferably a coherent or essentially coherent layer, of a barrier material comprising a) cellulose fibers having a number average length of 0.001 to 0.2 mm and a specific surface area from 1 to 100 m2 / g; b) an at least partially hydrolyzed vinyl acetate polymer; c) at least one anionic polymer; and optionally additional components, arranged on at least one side of the substrate.

The barrier material may originate from a self-supporting film of the present invention disposed on the substrate, or it may originate by coating the substrate with a layer of a fluid composition of the invention, preferably followed by removal of at least some of the water. of the flowable composition, to produce a barrier coating on the substrate.

In embodiments, a binder, such as an adhesive or thermoplastic, is used to bond the self-supporting film to the substrate.

The substrate on which the barrier material is arranged could be any substrate that could benefit from the barrier properties of the barrier material, that is, that is permeable to the entity (eg gas, vapor, moisture, grease, microorganisms , etc.) against which the barrier material forms a barrier. Examples of such substrates include, but are not limited to, plastic sheets and films, metallic or cellulosic materials, such as plastic films, metallic films, and sheets of paper or cardboard. Paper and cardboard are preferred materials for the substrate.

In addition to the aforementioned barrier material and the substrate, a multilayer article can comprise additional layers of different material arranged on at least one side of the multilayer article or between the barrier material and the substrate. Examples of such additional layers include, but are not limited to, layers of plastic and metallic materials.

The thickness of the barrier material in a multilayer article of the present invention is limited, on the one hand, by the minimum thickness required to obtain the desired barrier properties and, on the other hand, by the maximum thickness at which the layer can be produced. . When the barrier material originates from a self-supporting film as described above, the thickness restrictions of such a film apply. When the barrier material is obtained by coating the substrate with a flowable composition, the thickness of the barrier material is preferably 1, more preferably 2, to 20, preferably 10 pm.

A self-supporting film or multilayer structure of the present invention can be useful in many applications, for example in packaging applications where it is advantageous to retain gases, moisture, grease or microbes in a package or to keep gases, moisture, grease or microbes against entry into the package.

The present invention will now be further illustrated by the following non-limiting examples.

Example 1 (reference)

A) A film (1A) was produced from 100% microfibrillar cellulose (MFC) using a wire wound rod, supplied by BYK-Gardner GmbH, Germany, with a wet film thickness of 200 pm and a film width 200 mm. The film was formed on a polymer film and then allowed to dry at room temperature for 24 hours. The MFC was prepared from a bleached Fenton sulphite pulp pretreated from Domsjo pulp (40 ppm Fe2 +, ¹ % H ² O ² , pH 4, 70 ° C, 10% pulp consistency, 1 hour) passing the suspension of 1% fiber through a bead mill (Drais PMC 25TEX) (zirconium oxide beads, 65% fill grade, rotor speed 1200 rpm and flow rate 100 l / h). The characteristics of the MFC were as follows: fiber length: 0.08 mm and width: 27.2 pm (L&W fiber testing equipment), specific area of approximately 4 m2 / g (BET method using a Micromeritics ASAP 2010 instrument), stability: 100% (0.5% pulp suspension), water retention value (WRV): 3.8 (g / g) (SCAN: -C 62:00).

Unless explicitly stated otherwise, all percentages in the examples are calculated as% by weight based on the dry weight of the films.

B) A film (1B) was prepared as in A), but with 80% MFC and 20% polyvinyl alcohol, PVA 28-99 (Mw: 145,000, Dp: 3300) supplied by Aldrich.

C) A film (1C) was prepared as in A), but with 60% MFC and 40% polyvinyl alcohol.

D) A film (1D) was prepared as in A), but with 40% MFC and 60% polyvinyl alcohol.

E) A film (1E) was prepared as in A), but from 100% polyvinyl alcohol.

After drying, the films were removed from the polymer film, stored in a climatic room (23 ° C and 50% RH) for 24 hours and then their weight, thickness and strength properties were analyzed (ISO 536: 1995 , ISO 534: 1988, ISO 1924-2), shrinkage, water vapor transmission rate, WVTR (ASDTM E96-90) and oxygen transmission rate, OTR (ASTM F1307-90).

Shrinkage was measured by comparing the film area of the film before and after drying. A shrinkage value of 0 indicates that no shrinkage could be observed.

Table 1

From the results in Table 1 above, it can be concluded that film materials 1A and 1E are not suitable for use due to their shrinkage on drying. Another observation is also that film 1E depends on relative humidity to have a proper shape. Film materials 1B, 1C and 1D have a stable shape and show no shrinkage tendencies. These films also have much higher strength properties than 1A and especially 1E. The best overall film material when it comes to strength properties is 1C.

Example 2

A) A film (2A) was prepared as film 1A in Example 1, but with 60% MFC, 39.9% polyvinyl alcohol and 0.1% food grade xanthan gum with a charge density of 1, 25 meq / g (Particle Charge Detector, Mütek PCD 03) from Vendico Chemical AB (based on total film weight).

B) A film (2B) was prepared as film 2A, but with 60% MFC, 39.75% polyvinyl alcohol and 0.25% xanthan gum.

C) A film (2C) was prepared as film 2A, but with 60% MFC, 39.5% polyvinyl alcohol and 0.5% xanthan gum.

D) A film (2D) was prepared as film 2A, but with 60% MFC, 39.25% polyvinyl alcohol and 0.75% xanthan gum.

E) A film (2E) was prepared as film 2A, but with 60% MFC, 39% polyvinyl alcohol and 1% xanthan gum.

F) A film (2F) was prepared as film 2A, but with 60% MFC, 38.5% polyvinyl alcohol and 1.5% xanthan gum.

G) A film (2G) was prepared as film 2A, but with 60% MFC, 38% polyvinyl alcohol and 2% xanthan gum.

H) A film (2H) was prepared as film 2A, but with 60% MFC, 37% polyvinyl alcohol and 3% xanthan gum.

I) A film (2I) was prepared as film 2A, but with 60% MFC, 35% polyvinyl alcohol and 5% xanthan gum.

J) A film (2J) was prepared as film 1C in Example 1 (reference).

Analysis of the films was performed as described in Example 1

Table 2

From the results in Table 2 above, it can be concluded that 2D film material is significantly better than the other film materials when it comes to tensile strength and stiffness. Film 2E shows very good barrier properties, it should be noted that an OTR level of about 0.2 is currently in the same range as the best thermoplastic materials (EVOH) (Food and Packaging Materials - Chemical Interactions, ISBN 0-85404-720- 4).

Films containing xanthan gum (2A-2I) could be folded without cracking the film. Films 2A-2I appeared to be less brittle and more flexible than film 2J. Films 2A-2I appeared more impermeable than Film 2J, as tested by applying a drop of water to the films and observing its effect on the integrity of the film.

Furthermore, the film-forming properties were improved by the addition of xanthan gum, for example, a higher gloss of the films.

Example 3

A) A film (3A) was prepared as in film 2E in Example 2, but exchanging the xanthan gum for 1% CMC, Gambrosa PA 247 with a charge density of 2.2 meq / g AkzoNobel.

B) A film (3B) was prepared as in film 2E in Example 2, but exchanging the xanthan gum for 1% anionic starch, Glucapol 2030 with a charge density of 1.4 meq / g from Lyckeby Starkelse.

C) A film (3C) was prepared as in film 2E in Example 2, but exchanging the xanthan gum for 1% polyacrylic acid (Mw: 100,000) with a charge density of 3.2 meq / g supplied by Aldrich.

D) A reference film (3D) was prepared as in film 2E in Example 2, but exchanging the gum of xanthan by 1% Eka NP 442 with a charge density of 1.0 meq / g from Eka Chemicals AB.

E) A reference film (3E) was prepared as in film 2E in Example 2, but exchanging the xanthan gum for 1% Eka BSC 20 with a charge density of 0.7 meq / g from Eka Chemicals AB.

F) A reference film (3F) was prepared as in film 2E, but exchanging the xanthan gum for 1% guar gum, MEYPRO GUAR Cs Aa M-20, available from Danisco.

G) A reference film (3G) was prepared as film 1C in Example 1.

Analysis of the films was performed as described in Example 1

Table 3

From the results in table 3 above, it can be concluded that film materials in which different types of polymers / anionic products are used as additives have fairly equal strength properties. Another observation is that the deteriorated strength properties of the film are achieved when non-ionic guar gum (3F) is used as an additive.

Example 4

A) A film (4A) was prepared as film 1A in Example 1 but with 60% MFC, 39.5% polyvinyl alcohol and 0.5% Nano-fibers with a charge density of 0.8 meq / g prepared by TEMPO-mediated oxidation of bamboo fibers.

B) A film (4B) was prepared as film 1A in Example 1 but with 60% MFC, 39% polyvinyl alcohol and 1% Nano-fibers.

C) A film (4C) was prepared as film 1A in Example 1, but with 60% MFC, 38.5% polyvinyl alcohol and 1.5% Nano-fibers.

D) A film (4E) was prepared as in film 1A in Example 1, but with 60% MFC, 38% polyvinyl alcohol and 2% Nano-fibers.

E) A film (4E) was prepared as in film 1A in Example 1, but with 60% MFC, 37.5% polyvinyl alcohol and 2.5% Nano-fibers.

F) A film (4F) was prepared as film 1A in Example 1, but with 60% MFC, 37% polyvinyl alcohol and 3% Nano-fibers.

G) A reference film (4G) was prepared as film 1A in Example 1, but with 60% MFC, 36% polyvinyl alcohol and 4% Nano-fibers.

H) A reference film (4H) was prepared as film 1A in Example 1, but with 60% MFC, 35% polyvinyl alcohol and 5% Nano-fibers.

I) A reference film (4I) was prepared as film 1C in Example 1.

Analysis of the films was performed as described in Example 1

Table 4

From the results in Table 4 above, it can be concluded that all film materials are equal in strength properties, but 4F material is significantly better than the other materials when it comes to OTR.

Example 5

A) A film (5A) was prepared as film 1A in Example 1, but from 58% MFC, 40% polyvinyl alcohol, 1% xanthan gum and 1% of the 1: 1 formulation (p / p) RDS-Laponite (from Rockwood) / Eka NP 320 (from Eka Chemicals).

B) A film (5B) was prepared as film 5A but from 58% MFC, 40% polyvinyl alcohol, 1% xanthan gum and 1% of the formulation of 1: 1 (w / w) RDS- Laponit / Eka NP 2180.

C) A film (5C) was prepared as 5A film, but from 58% MFC, 40% polyvinyl alcohol, 1% xanthan gum and 1% Eka NP 2180.

D) A film (5D) was prepared as 5A film but from 58% MFC, 40% polyvinyl alcohol, 1% xanthan gum and 1% RDS-Laponite.

E) A reference film (4I) was prepared as film 1C in Example 1.

Analysis of the films was performed as described in Example 1

Table 5

From the results in Table 5 above, it can be concluded that the 5A film material is significantly better than the other film materials with respect to strength properties. Films 5B and 5C show excellent OTR properties.

Claims (20)

1. A composition comprising a) cellulose fibers, having a number average length of 0.001 to 0.2 mm and a specific surface area of 1 to 100 m2 / g and comprising microfibrillar cellulose fibers; b) an at least partially hydrolyzed vinyl acetate polymer; and c) at least one anionic polymer wherein the composition comprises 55 to 65% by weight of a) and 35 to 45% by weight of b) based on the dry weight of a) and b) in the composition; as well as 0.1 to 3% by weight of c), based on the dry weight of a), b) and c) in the composition. 2. A composition according to any one of the preceding claims, further comprising: d) nanoparticles or microparticles. 3. A composition according to any one of the preceding claims, wherein said at least partially hydrolyzed vinyl acetate polymer has a degree of hydrolyzation of at least 90%. 4. A composition according to any one of the preceding claims, wherein said at least partially hydrolyzed vinyl acetate polymer is a polyvinyl alcohol with a degree of hydrolyzation of at least 90%. 5. A composition according to any one of the preceding claims, wherein said anionic polymer comprises a polysaccharide. 6. A composition according to claim 5, wherein said polysaccharide comprises an anionic polysaccharide gum. 7. A composition according to any of the preceding claims, comprising 50 to 99.9% by weight of water, based on the total weight of the composition. 8. A method of producing a self-supporting film, comprising forming a film from a composition according to claim 7 on a support surface; remove at least part of the water from said composition; removing the self-supporting film thus formed from said supporting surface. A method according to claim 8, wherein the self-supporting film thus formed comprises at most 50, preferably at most 20% by weight of water. 10. A self-supporting film comprising a composition according to any one of claims 1 to 6. 11. A self-supporting film according to claim 10 having a thickness of 1 to 1000 pm, preferably 10 to 100 pm. 12. A self-supporting film according to claim 10 or 11, comprising at most 50, preferably at most 20% by weight of water. 13. A multilayer article comprising a substrate and a composition according to any one of claims 1 to 6 or a self-supporting film of any one of claims 10 to 12 arranged on at least one surface of said substrate. A multilayer article according to claim 13, wherein said substrate is a sheet of paper or cardboard. 15. A method for the production of a multilayer article, comprising the steps of: provide a substrate; and (i) providing a self-supporting film according to any one of claims 10 to 12; and disposing said self-supporting film on said substrate; or (ii) providing a composition according to claim 7, and applying a layer of said composition on at least one side of said substrate. 16. A method according to claim 15, wherein said substrate is a sheet of paper or cardboard. 17. A method of claim 15 or 16, wherein step (ii) further comprises removing at least part of the water from said composition applied to said substrate such that said layer then comprises at most 50, preferably at most 20% by weight of water. 18. A method of claim 17, wherein said layer comprising at most 50, preferably at most 20% by weight of water, has a thickness of 1 to 20, preferably 2 to 10 pm. 19. Use of a composition according to any one of claims 1 to 7 or a self-supporting film according to any one of claims 9 to 12, to provide a barrier to a permeable substrate. 20. The use according to claim 19, wherein said permeable substrate is a sheet of paper or cardboard.